A number of display types exist for the purpose of physically displaying a representation of an image formed electronically, such as on a computer. Standard Cathode-Ray Tube (CRT) displays are the most common, but are supplemented by technologies such as Liquid Crystal Display (LCD) and gas plasma display when space is a concern. Each of these display types has characteristics that are advantageous for certain applications, but all share certain characteristics that limit the use of electronic displays to certain applications.
A standard CRT display used with most personal computer systems receives three signals of varying intensity, each representing one of the colors red, green, and blue. The strength of each signal controls the intensity of an electron stream produced by an electron gun within the CRT. The electron streams are focused and aimed by a magnetic deflection apparatus, which receives signals from the video source that control the deflection apparatus to sweep each electron beam from side to side in a pattern that crosses and moves down the screen. The beams pass through a shadow mask, a metal plate comprising a number of small holes or slots, used to keep the electron beams precisely focused on the target. The beams then strike phosphor which coats the inside of the screen, and create a visible image. Separate phosphors exist for each of the three colors, and glow with intensity proportional to the intensity of the striking electron beam. This CRT apparatus is well-understood and relatively inexpensive, but is physically large in size, and its resolution is limited by the slot mask and screen phosphor geometry.
A popular alternative is a Liquid Crystal Display (LCD). Such a display operates by first generating light from a fluorescent panel near the back of the display. A polarizing filter in front of the light panel passes only those light waves that are vibrating in or near a particular plane, most commonly horizontal. The polarized light then passes through a layer of liquid crystal cells. Each of the cells may be electronically activated by varying voltages, such that a cell receiving no voltage has no twist in the crystal structure of the liquid crystal cell, while a cell receiving a high voltage has about 90 degrees of twist in the crystal structure of the liquid crystal cell. Polarized light entering the rear of the cells follows the structure of the liquid crystal, turning up to 90 degrees in orientation with the twist in the crystal structure. The light then passes through a color filter that is either red, blue, or green, and through a second polarizing filter oriented at 90 degrees rotated from the first polarizing filter. Light that is not oriented essentially in the same plane as the second polarizing filter is attenuated, and light that vibrates at 90 degrees from the orientation of the second filter is blocked almost completely. Therefore, by varying the voltage applied to the liquid crystal cell, the light transmitted through the display is varied proportionately, and an array of such devices is used to produce an image. Such a display can be quite flat, but resolution is again limited by the physical size of the polarizing and color filters, and the liquid crystal cell.
Other display mechanisms exist, but most have some physical attribute that limits the resolution displayable by the apparatus. What is needed is a display apparatus that allows real-time creation of very high-resolution images.